Process for forming an electrically conductive coating on a nonmetallic filament

ABSTRACT

A PROCESS FOR FORMING AN ELECTRICALLY CONDUCTIVE COATING ON THE SURFACE OF A NONMETALLIC FILAMENT, CHARACTERIZED IN THAT SAID NONMETALLIC FILAMENT IS CARRIED BY ELECTRICALLY CONDUCTIVE MEMBERS AND PLACED IN AN ELECTRO-DEPOSITING COATING MATERIAL COMPRISING ELECTRICALLY CONDUCTIVE PARTICLES DISPERSED IN A RESINUOUS CARRIER WITH A CONCENTRATION OF 15-25%, PREFERABLY 18-20% BY WEIGHT, SAID CONDUCTIVE MEMBERS WHICH SERVE AS ONE ELECTRODE AND THE OTHER ELECTRODE LOCATED IN SAID ELECTRO-DEPOSITING COATING MATERIAL BEING ELECTRIFIED WITH A D.C. VOLTAGE, THEREBY FORMING A COATING OF A UNIFORM AND DESIRED THICKNESS ON THE SURFACE OF SAID NONMETALLIC FILAMENT. IN THE PROCESS ACCORDING TO THIS INVENTION, AN ELECTRIC CONDUCTOR UMPLOYING A NONMETALLIC FILAMENT AS A CARRIER OR BASE AND HAVING A DESIRED ELECTRIC RESISTANCE CAN BE EASILY AND SURELY OBTAINED BY CONTROLLING THE D.C. VOLTAGE, CURRENT DENSITY OR ELECTRIFYING PERIOD FOR ELECTRO-DEPOSITION, EMPLOYING SIMPLE AND ECONOMICAL ELECTRO-DEPOSITING COATING DEVICES.

8 14, 1973 'MASANAO HIROSE 3,752,751

PROCESS FOR FORMING AN ELECTRICALLY CONDUCTIVE COATING ON A NONMETALLIC FILAMENT Filed Jan. 8. 1971 2 Sheets-Sheet 1 l I l l 1 l I INVENTOR,

ww/vigm 1973 MASANAO HIROSE 3,752,751

PROCESS FOR FORMING AN ELECTRICALLY CONDUCTIVE COATING ON A NONMETALLIC FILAMENT Filed Jan. 8. 1971 1 2 Sheets-Sheet 2 United States Patent Ot'fioe 3,752,751 Patented Aug. 14, 1973 3,752,751 PROCESS FOR FORMING AN ELECTRICALLY CONDUCTIVE COATING ON A NONMETALLIC FILAMENT Masanao Hirose, 2-9-93 Kodo, Adachi-ku, Tokyo, Japan Filed Jan. 8, 1971, Ser. No. 104,855 Claims priority, application Japan, Mar 20, 1970, 45/23,389 Int. Cl. BOlk 5/02 US. Cl. 204-181 Claims ABSTRACT OF THE DISCLOSURE A process for forming an electrically conductive coating on the surface of a nonmetallic filament, characterized in that said nonmetallic filament is carried by electrically conductive members and placed in an electro-depositing coating material comprising electrically conductive particles dispersed in a resinuous carrier with a concentration of -25%, preferably 18-20% by weight, said conductive members which serve as one electrode and the other electrode located in said electro-depositing coating material being electrified with a DC. voltage, thereby forming a coating of a uniform and desired thickness on the surface of said nonmetallic filament. In the process according to this invention, an electric conductor employing a nonmetallic filament as a carrier or base and having a desired electric resistance can be easily and surely obtained by controlling the DC. voltage, current density or electrifying period for electro-deposition, employing simple and economical electro-depositing coating devices.

This invention relates to a process for forming an electrically conductive coating on nonmetallic filaments.

Heretofore, as the process for forming a coating on the surface of metals, a method of electro-deposition is generally employed, but so far as nonmetallic filaments are concerned, there is adopted only a method of simply dipping same into a solution of coating material to form a coating thereon. In this method, however, it is rather difficult to obtain a coating of a uniform thickness as com pared with coating by an ordinary electro-deposition and at the same time to control the thickness of said coating as desired.

The coating by electro-deposition means, as its general definition, applying a coating to the surface of an electric conductor taking advantage of the polarization of the coating material within an electric field. On the other hand, in the present invention, the electric conductivity of said electrically conductive coating material as well as the adhesive property thereof to the surface of nonmetallic filaments is taken advantage of, and a coating by electro-deposition is applied to an organic or inorganic filament which is a nonmetallic substance, by placing an electrode on the filament itself.

In view of the foregoing, it is an object of the present invention to provide a process for forming a coating of a uniform and desired thickness on the surface of nonmetallic filaments by applying an electric voltage between members for supporting said nonmetallic filaments placed in an electro-depositing coating material and the same coating material itself which serves as an electric conductor.

The primary gist of the present invention lies in a process for forming an electrically conductive coating on the surface of a nonmetallic filament, characterized in that said nonmetallic filament is supported by electrically conductive members and is placed in an electro-depositing coating material comprising electrically conductive particles dispersed in a resinous carrier with a concentration of 15-25%, preferably 18-20% by weight, said conductive members which serve as one electrode and the other electrode located in said electro-depositing coating material being electrified with a DC voltage, thereby forming a coating of a uniform and desired thickness on the surface of said nonmetallic filament, said electrically conductive particles being selected from the group consisting of a magnetic metal, metallic oxide, metallic silicate and nonmetallic particles and being employed alone except a metal or in combination, said resinous carrier including a synthetic resin having high-frequency dielectric constant.

Various further objects, features and advantages of the present invention will be made apparent from the following description taken in connection with the accompanying drawings, in which;

FIG. 1 is a diagrammatic elevation view of a fixed type electro-depositing coating device which is one embodiment of this invention, partly shown in cross section;

FIG. 2 is a diagrammatic elevation view of a continuous type electro-depositing coating device which is another embodiment of this invention, partly shown in cross section; and

FIG. 3 is a circuit diagram of a continuous proportional control unit which is an electric source for the device shown in FIG. 2.

Referring now to FIG. 1, numeral 1 designates a piece of nonmetallic filament made of synthetic fibre, for example, glass fibre, acrylonitrile fibre, polyester type fiber, nylon-type fibre etc. by intertwisting six strands of 1000 denier to form one filament. Said nonmetallic filament is carried by metal clips 2. Numeral 3 is a carbon electrode, 4 and 5 are electric terminals, 6 is an agitator, 7 is an electrO-depositing coating material and 8 is a glass container.

Referring to FIG. 2, there is illustrated a continuous type electro-depositing coating device. Numeral 1 is a piece of nonmetallic filament of the same material as above-mentioned, and 9 is a guide pulley. Numerals 10 and 11 are pulleys which are made of composition of graphite and phenol resin and serve as electrically conductive means. Numerals 12 and 13 are guide pulleys for the coated nonmetallic filament.

Letters X and Y designate pulleys for an electric conduction test which are adapted to measure the electric resistance of the electric conductor and are connected to terminals of a continuous proportional control unit shown in FIG. 3. Number 3 is a carbon electrode, 4 and 5 are electric terminals, 8 is a glass container and 14 is a ner.

The present invention is further illustrated by the following examples which should not be construed to limit the scope of the present invention.

EXAMPLE 1 The electro-depositing coating device shown in FIG. 1 Was operated by a DC voltage generated from the control unit shown in FIG. 3. A piece of glass filament yarn 1 was carried by the clips 2 and electric voltage was applied to the terminals 4 and 5 respectively. In the coating material consisting of 50 parts of water soluble phenol resin, 200 parts of pure water and 100 parts of mixture of Fe, Fe O Fe O and FeO-Si0 mixed in amounts of 5%, 5%, and 10% by weight, respectively and having a particle size passable through a sieve of 400-450 meshes, the electro-deposition was attained by applying DC 30 v. of electric voltage to the terminals 4 and 5 and by electrifying with about 270 ma. of electric current for 5 minutes.

The thus obtained linear electro-conductive magnetic substance showed an electric resistance of 30 Mal/100 mm. It was magnetized when a magnet was drawn near and demagnetized the instant the magnet was withdrawn.

EXAMPLE 2 The continuous type electro-depositing coating device shown in FIG. 2 was operated to obtain an electrodeposited coating continuously on a piece of glass filament yarn. The reeled-off filament yarn 1 was introduced through the guide pulley 9 and electro-deposited through the pulleys 10 and 11. The anode was set on said pulleys 10 and 11, While the cathode was set on the carbon electrode 3. The electro-deposited filament yarn 1 was dried and stiffened by the drier 14 while passing through the guide pullley 12 and 13.

The electric resistance was measured in the course of transfer at the points of X and Y, and the electrodepositing voltage was controlled by the continuous proportional control unit to uniformalize the electric resistance of the electric conductor obtained.

The accomplished filament yarn may be further covered with a protective coating by an ordinary skill in the art or may be utilized, as it is, as an electric conductor.

The coating material employed in this example consisted of 50 parts of Water soluble melamine resin, 100 parts of mixture of Fe, Fe O Fe O and iFeO-SiO mixed in the same amounts as in Example 1 and 200 parts of pure water. The electric voltage was DC 70 v., the electric current was 900 ma. and the haul-oft speed of the glass filament yarn was 10 mm./sec.

The thus obtained linear electro-conductive magnetic substance showed an electric resistance of 20 MSZ/ 100' mm. and was magnetized in the same manner as in the former example.

EXAMPLE 3 In the same manner as described in Example 1, electrodeposition was attained in the coating material of 20 parts of water soluble phenol resin, 200 parts of pure water and 50 parts of carbon particles by applying DC 30 v. and 350 ma. for 3 minutes.

The electric resistance of the obtained linear electroconductive filament was 1000 100 mm.

EXAMPLE 4 In the same manner as described in Example 2, electrodeposition was attained in the coating material of 50 parts of water soluble urea resin, 100 parts of graphite particles and 200 parts of pure water by applying DC 60 v. and 950 ma. at a haul-off speed of 10 mm./ sec.

The electric resistance of the obtained linear electric conductor was 1.2 K 0/100 mm.

EXAMPLE 5 In the same manner as described in Example 1, electro-deposition was attained in the coating material of 50 parts of water soluble phenol resin, 200 parts of pure water, 90 parts of mixture of Fe O Fe O FeO-SiO Bao and 2110 mixed in amounts of 5%, 82%, 5%, 3% and 5% by weight, respectively and having the same particle size as in Example 1, and parts of carbon by applying DC 20 v. and 350 ma. for 4 minutes.

The obtained linear electric conductor showed an electric resistance of 7 K 52/100 mm. and proved to be a magnetic substance.

EXAMPLE 6 In the same manner as described in Example 2, electroeposition was a tained in the coating material of 30 parts of water soluble phenol resin, 10 parts of water soluble melamine resin, 50 parts of mixture of Fe, Fe O Fe O and FeO-Si0 mixed in amount of 5%, 8%, 77% and 10% by weight, respectively and having the same particle size as in Example 1, 10 parts of carbon, 10 parts of graphite and 200 parts of pure water by applying DC 65 v. and 1100 ma. at a haul-off speed of 10 mm./sec.

The obtained linear electric conductor showed an electric resistance of 1.2 k. 52/100 mm. and proved to be a magnetic substance.

The process according to the present invention has such notable features that an electric conductor of non-metallic filament having a desired resistance can be easily and surely obtained by controlling DC voltage voltage, electric current density or electrifying period for electrodeposition.

What is claimed is:

1. A process for forming an electrically conductive coating on the surface of a nonmetallic substrate which initially is nonconductive, which comprises the steps of:

supporting said substrate on a plurality of spaced-apart electrically conductive members with said substrate and at least parts of said conductive members being submerged in an aqueous liquid bath of electrodepositable coating material, said liquid bath comprising electrically conductive particles dispersed in an aqueous carrier liquid containing synthetic resin material, said bath also containing an electrode submerged therein and spaced from said substrate and said electrically conductive members;

applying DC electrical potential between (1) said electrically conductive members and (2) said electrode, until there is formed an electrically conductive coating of substantially uniform thickness on said substrate.

2. A process as claimed in claim 1, in which said substrate is a filament.

3. A process as claimed in claim 2, wherein said electrically conductive members are metal clips submerged in said bath and to which said filament is attached so as to be stationary in said bath, said metal clips and said electrode being electrified with DC potential for a predetermined period to form an electrically conductive coating on the stationary filament.

4. A process as claimed in claim 2, wherein said electrically conductive members are electrically conductive pulleys for carrying and moving the filament, said pulleys and said electrode being continuously electrified with DC potential, thereby forming an electrically conductive coating on said nonmetallic filament during the course of movement thereof by the pulleys at a predetermined speed.

5. A process as claimed in claim 4, including the further steps of measuring the electric resistance of the obtained electrically conductive filament after it has passed through said bath, and controlling the DC voltage applied between said pulleys and said electrode, thereby imparting to the obtained electrically conductive filament a uniform electric resistance.

6. A process as claimed in claim 1, in whcih said bath consists essentially of said electrically conductive particles, said synthetic resin and water.

7. A process as claimed in claim 6, in which said synthetic resin is water-soluble synthetic resin dissolved in said water.

8. A process as claimed in claim 7, in which said electrically conductive particles consist of a conductive material selected from the group consisting of magnetic metal, metallic oxide, metallic silicate, nonmetallic conductive particles and mixtures thereof.

9. A process as claimed in claim 8, in which said electrically conductive members are connected to the negative terminal of a DC potential source and said electrode is co ne ed to the positive side of the DC potential source.

6 10. A process as claimed in claim 8, in which said R f n s Cited resin is selected from the group consisting of phenol resin, melamine resin, urea resin and mixtures thereof, UNITED STATES PATENTS and in which said electrically conductive particles are 03 5/1955 Dorst 204-181 selected from the group consisting of Fe, Fe O Fe O 5 2,898,279 8/1959 Metcalfe et a1. 204--181 FeO-SiO carbon, graphite, BaO, ZnO and mixtures thereof. HOWARD S. WILLIAMS, Primary Examiner UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 752 751 D t d August 14, 1973 Inventorifi MaSanaO HirOSe It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Please insertinto the heading: -Assigned to Yazaki Corporation of Tokyo, Japan.-.

Signed andvse aled this 12th day of Febrnary 1974.

(SEAL) Attestz EDWARD M.FLETCHER-JR. I Att'esting Officer C MARSHALL DANN Commissioner of Patents oam PO-1050 (10-69) uscoMM-oc 60876-P69 a 0.5, GOVERNMENT PRINT NG OFFICE: IBIS 0-366-334, I u/ 

